1. Field of the Invention
The invention relates to a cylinder head for an air-cooled internal combustion engine having its intake duct and its exhaust duct each arranged transversely to the direction of cooling air flow and having groups of cooling fins arranged perpendicularly and parallel with regard to the cylinder axis, the cylinder head also including air-leading surfaces, and the lower region of the cylinder head below the intake and the exhaust ducts being provided with cooling fins oriented perpendicularly to the cylinder axis and extending from the front to the backside of the cylinder head in the direction of the air flow, the upper region of the cylinder head between the valve guides including a group of cooling fins arranged to extend parallel to the cylinder axis, at the height of the intake and the exhaust ducts on the sides of the afflux of cooling air and on both sides of the cooling fins oriented to extend parallel to the cylinder axis there being further provided a group of cooling fins oriented perpendicularly with respect to the cylinder axis and extending to the walls of the intake and exhaust ducts respectively, and at the exit for the cooling air there being arranged a group of cooling fins oriented to extend parallel to the cylinder axis, and on the side of the afflux of cooling air there being provided air-leading surfaces, these air-leading surfaces forming outlets on the sides of the cylinder head for a part of the cooling air, and above the cylinder head these being arranged a further air-leading surface extending over the cooling fins located with respect to the direction of the cooling air flow in front and behind the intake and the exhaust ducts.
2. Description of the Prior Art
With known embodiments of the kind described above the intake and the exhaust duct are each arranged to extend transversely to the crankshaft axis for various reasons, and primarily due to construction limitations. Cooling air is supplied by a flywheel blower and is blown in a direction parallel to the crankshaft axis over the cylinder head. Due to the arrangement of the intake and the exhaust ducts, these structures will constitute an obstacle for the cooling air so that the parts of the cylinder head lying lee of the ducts are not cooled in a satisfactory fashion. In addition, the cooling air reaching the backside of the cylinder head will be already heated up, and as a consequence, the parts of the cylinder head in the region of the exit for the cooling air will less effectively cooled. Engines of the kind referred to are often subject to cooling problems of their cylinder heads.
Certain improvements in these conditions can be gained with a construction of a cylinder head published in DE-OS No. 1930 148. The cylinder head described in this German document has at the height of the intake and the exhaust ducts on the sides of the afflux of cooling air, a group of cooling fins oriented to extend parallel to the cylinder axis, and on both sides of each group a further group of cooling fins is arranged to extend perpendicularly to the cylinder axis, the cooling fins respectively extending to the walls of the intake and the exhaust ducts. At the exit for the cooling air a further group of cooling fins is provided which extend parallel to the cylinder axis, and on the side of the afflux of cooling air, air-leading surfaces are arranged which form outlets on the sides of the cylinder head for a part of the cooling air, which outlets are located in front of the walls of the intake and the exhaust ducts. Above the cylinder head a further air-leading surface is provided which extends over the cooling fins located with respect to the direction of the cooling air flow in front and behind the intake and the exhaust ducts and which air-leading surface is cast integrally with the cooling fins.
This construction is afflicted with the essential disadvantage that due to the integral casting of the cylinder head and the thereabove-arranged air-leading surface, production of the cylinder head is more difficult. Because of the relatively large cooling air conduits in the region of the cooling air exit and because of the lack of lateral air leading surfaces behind the intake and the exhaust ducts, cooling of this part of the cylinder head is unsatisfactory.